Apparatus for regulating steam pressure in a fuel cell system

ABSTRACT

A steam pressure regulator for a reformer of a fuel cell system. The reformer includes an inlet in fluid communication with a steam source, and an outlet that provides a supply of hydrogen gas. The steam pressure regulator including a valve body, a valve movable between first and second positions, and an actuator. The valve body defines an internal flow passage between first and second ports. The first port is adapted to be in fluid communication with the inlet of the reformer. The first position of the valve substantially prevents fluid communication through the internal flow passage, and the second position of the valve permits generally unrestricted fluid communication through the internal flow passage. The actuator includes an actuator body that defines a chamber, a movable actuator wall that divides the chamber into first and second chamber spaces, and a shaft that couples the movable actuator wall to the valve. The shaft includes a signal passage that provides fluid communication between the first port and the first chamber space, such that fluid pressure at the first port is communicated through the signal passage to the first chamber space.

FIELD OF THE INVENTION

[0001] This disclosure relates to a steam pressure regulator, and moreparticularly, to a steam pressure regulator for use in a fuel cellsystem.

BACKGROUND OF THE INVENTION

[0002] It is believed that a fuel cell includes two electrodessandwiched around an electrolyte. It is believed that oxygen, e.g., fromair, passes over one electrode and hydrogen, e.g., from a hydrogensource, passes over the other electrode, and in a chemical reaction,generates electricity.

[0003] It is also believed that the hydrogen source can be a reformerthat produces hydrogen gas as one product of another chemical reaction.It is believed that one type of reformer uses steam, oxygen, andgasoline to produce hydrogen, carbon dioxide, and carbon monoxide. Thus,it is believed that there is a need to regulate the steam pressuresupplied to a reformer in a fuel cell system.

SUMMARY OF THE INVENTION

[0004] The present invention provides a steam pressure regulator for areformer of a fuel cell system. The reformer includes an inlet in fluidcommunication with a steam source, and an outlet that provides a supplyof hydrogen gas. The steam pressure regulator including a valve body, avalve movable between first and second positions, and an actuator. Thevalve body defines an internal flow passage between first and secondports. The first port is adapted to be in fluid communication with theinlet of the reformer. The first position of the valve substantiallyprevents fluid communication through the internal flow passage, and thesecond position of the valve permits generally unrestricted fluidcommunication through the internal flow passage. The actuator includesan actuator body that defines a chamber, a movable actuator wall thatdivides the chamber into first and second chamber spaces, and a shaftthat couples the movable actuator wall to the valve. The shaft includesa signal passage that provides fluid communication between the firstport and the first chamber space, such that fluid pressure at the firstport is communicated through the signal passage to the first chamberspace.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The accompanying drawings, which are incorporated herein andconstitute part of this specification, illustrate presently preferredembodiments of the invention, and, together with the general descriptiongiven above and the detailed description given below, serve to explainfeatures of the invention.

[0006]FIG. 1 is a schematic illustration of a system, in accordance withthe present invention, including a fuel cell and a pressure regulator.

[0007]FIG. 2 is a cross sectional view of a pressure regulator inaccordance with the present invention.

[0008]FIG. 3 is a cross sectional view of a detail of the pressureregulator shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0009] Referring to FIG. 1, there is shown a system 10 according to thepresent invention. As used herein, like numerals indicate like elementsthroughout. The system 10 includes a reformer 20, a source of steam 30,a source of oxygen 35, a source of gasoline 40, a fuel cell 45, and apressure regulator 50. The reformer 20 can include a first inlet 22 influid communication with the steam source 30, a second inlet 24 in fluidcommunication with the oxygen source 35, and a third outlet 28 in fluidcommunication with the gasoline source 40. The reformer 20 can alsoinclude an outlet 28 from which hydrogen gas is supplied to the fuelcell 45. In the fuel cell 45, a chemical reaction using the hydrogengenerates electrical energy, as is known.

[0010] Referring also to FIG. 2, the pressure regulator 50 is coupledfor steam communication to the first inlet 22 of the reformer 20.According to a preferred embodiment, the pressure regulator 50 branchesoff a steam line coupling the steam source 30 and the first inlet 22 ofthe reformer 20. The pressure regulator 50 includes a valve body 60defining an internal flow passage 62 between an inlet port 64 and anoutlet port 66. The internal flow passage 62 can be at least partiallydefined by a valve seat 68 fixed to the valve body 60. The inlet port 64is coupled for fluid communication with the outlet 28 of the fuel cell20, and the outlet port 66 is coupled for fluid communication with theambient environment. Of course, fluid communication can be achievedthrough any know types of passages, conduits, pipes, etc., or theirequivalents. According to the preferred embodiment illustrated in FIG.2, the inlet and outlet ports 64,66 are oriented at 90 degrees withrespect to one another. Of course, other relative orientations, e.g.,in-line, are also possible. The valve body 60 can be constructed ofmetal, plastic, or an equivalent material that does not react adverselyto contact with steam.

[0011] A valve 70 is movable with respect to the valve body 60 so as tocontrol fluid communication through the internal flow passage 62. Thevalve 70 can be a poppet that is displaceable with respect to the valveseat 68 between first and second positions. In the first position of thevalve 70 with respect to the valve seat 68, as shown in FIG. 2, fluidcommunication through the internal flow passage 62 is substantiallypreventing by virtue of the valve 70 sealingly engaging the valve seat68. In the second position of the fluid of the valve 70 with respect tothe valve seat 68, not shown, fluid communication through the internalflow passage 62 is generally unrestricted by virtue of the valve 70being spaced from the valve seat 68. The valve 70 can be constructed ofmetal, plastic, or an equivalent material that does not react adverselyto contact with steam.

[0012] An actuator 80 can be used to control movement of the valve 70between the first and second positions. The actuator 80 can include anactuator body 82 defining a chamber 84, a movable actuator wall 90dividing the chamber 84 into a first chamber space 84 a and a secondchamber space 84 b, and a shaft 100 coupling the movable actuator wall90 to the valve 70. The actuator body 82 can be constructed of metal,plastic, or an equivalent material.

[0013] The first chamber space 84 a is in fluid communication with theinlet port 64 such that changes in steam pressure at the inlet port 64can vary the volume of the first chamber space 84 a by displacing themovable actuator wall 90.

[0014] A resilient element, e.g., a coil spring 86, is located in thesecond chamber space 84 b and extends between the actuator body 82 andthe movable actuator wall 90. The coil spring 86 presents a spring forceopposing the steam pressure expanding the volume of the first chamberspace 84 a. According to the preferred embodiment illustrated in FIG. 2,a vent port 88 can provide fluid communication between the secondchamber space 84 b and the ambient environment.

[0015] The movable actuator wall 90 can include a diaphragm 92 flexiblycoupling an outer portion 94, which is sealed with respect to theactuator body 82, and an inner portion 96, which is fixed to the shaft100. In a preferred embodiment, the movable actuator wall 90 issubstantially fluid impermeable and the inner portion 96 includes arelatively rigid disk contiguously engaged by the spring 86. Thediaphragm 92 can be constructed of rubber, a polymer, or an equivalentmaterial that is sufficiently flexible to accommodate the relativemovement of the inner and outer portions 94,96.

[0016] According to the preferred embodiment illustrated in FIG. 2 and3, the valve 70 and the shaft 100 define a signal passage 102 providingfluid communication between the inlet port 64 and the first chamberspace 84 a. The signal passage 102 can include a signal port 104 in aface 72 of the valve 70 (the face 70 is in fluid communication with theinlet port 64 in the first position of the valve 70), a longitudinalchannel 106 extending along a longitudinal axis of the shaft 100, and atransverse channel 108 providing fluid communication between thelongitudinal channel 106 and the first chamber space 84 a.

[0017] One or more guides 110 can support the shaft 100 for longitudinalsliding with respect to the valve body 60. According to the preferredembodiment illustrated in FIG. 2, two guides 110, e.g., antifrictionbearings, facilitate smooth movement of the shaft 100 relative to thevalve body 60. Of course, any number of guides 110 can be used, and canbe separately fitted to, or integrally formed with, the valve body 60.Additionally, a guide 110 (the upper guide 110 shown in FIG. 2) canprovide a substantially fluid tight seal with respect to the shaft 100and thus partially define the first chamber space 84 a. Alternatively, aseal separate from the guide(s) 110 can be used to enclose the firstchamber space 84 a with respect to the shaft 100, and the guide(s) 110could have any arrangement, e.g., permitting fluid flow, that supportsthe shaft 100 for movement relative to the valve body 60

[0018] According to the preferred embodiment illustrated in FIG. 2, thevalve body 60 can be fastened to the actuator body 82 via anintermediate body 120. The intermediate body 120 can be separatelyfitted to the valve and actuator bodies 60,82, or as shown in FIG. 2,can be integrally formed with either one of the valve and actuatorbodies 60,82. The intermediate body 120 can include one or more fins 122(four are illustrated) projecting into the ambient conditions around theintermediate body 120. These fins 122 can be separately mounted on acylindrical body 124 that is fitted to the intermediate body 120, or maybe integrally formed with the intermediate body 120. The fins 122 can bein the shape of an annulus lying in an imaginary plane that isperpendicular to the longitudinal axis of the shaft, and have an insidediameter of the annulus fixed to the intermediate body 120 or to thecylindrical body 124. Of course, there can be any number, shape (e.g.,not a complete annulus), or arrangement of the fin(s) 122 fordissipating into the ambient conditions heat that would otherwise beconducted from the valve body 60 to the actuator 80. Dissipating thisheat can be beneficial in protecting the movable actuator wall 90, e.g.,avoiding damage to the flexible diaphragm 92 that could otherwise betransferred from steam in the internal flow passage 62. The intermediatebody 120 or fin(s) 122 can be constructed of metal, e.g., aluminum ormagnesium, or an equivalent material suitable for dissipating heat tothe ambient environment.

[0019] The operation of the system 10 will now be described. Steam issupplied from the steam source 30, via the first inlet 22, to thereformer 20, oxygen is supplied from the oxygen source 35, via thesecond inlet 24, to the reformer 20, and gasoline is supplied from thegasoline source 40, via the third inlet 28, to the reformer 20. Thereformer 20 uses the steam, oxygen, and gasoline in a chemical reactionthat generates hydrogen gas that is supplied, via the outlet 28, to thefuel cell 45. Other products of this chemical reaction, e.g., carbondioxide or carbon monoxide, can be otherwise expelled from the reformer20.

[0020] The pressure regulator 50 establishes a predetermined level ofsteam pressure at the first inlet 22. In particular, steam pressure fromthe steam source 30 is communicated by the signal passage 102 to thefirst chamber space 84 a, and when the predetermined level of steampressure is achieved, the movable actuator wall 90 is displaced againstthe opposing spring force of the coil spring 86. This displacement ofthe movable actuator wall 90 is conveyed via the shaft 100 to the valve70, which is displaced from the valve seat 68 so as to provide fluidcommunication through the internal flow passage 62 and thereby ventsteam pressure in excess of the predetermined level of steam pressure tothe ambient environment through the outlet port 66.

[0021] Setting the predetermined level of steam pressure is achieved byadjusting the spring force of the coil spring 86. Increasing the springforce sets a higher predetermined level of steam pressure, anddecreasing the spring force sets a lower predetermined level of steampressure. The spring force can be adjusted by interchanging coil springs86 having different spring rates, or by varying pre-compression of thecoil spring 86 between the actuator body 82 and the movable actuatorwall 90.

[0022] While the present invention has been disclosed with reference tocertain preferred embodiments, numerous modifications, alterations, andchanges to the described embodiments are possible without departing fromthe sphere and scope of the present invention, as defined in theappended claims. Accordingly, it is intended that the present inventionnot be limited to the described embodiments, but that it have the fullscope defined by the language of the following claims, and equivalentsthereof.

What is claimed is:
 1. A steam pressure regulator for a reformer of afuel cell system, the reformer including an inlet in fluid communicationwith a steam source, and an outlet providing a supply of hydrogen gas,the steam pressure regulator comprising: a valve body defining aninternal flow passage between first and second ports, the first port isadapted to be in fluid communication with the inlet of the reformer; avalve movable between first and second positions, the first positionsubstantially preventing fluid communication through the internal flowpassage, and the second position permitting generally unrestricted fluidcommunication through the internal flow passage; and an actuatorincluding: an actuator body defining a chamber; a movable actuator walldividing the chamber into first and second chamber spaces; and a shaftcoupling the movable actuator wall to the valve, the shaft including asignal passage providing fluid communication between the first port andthe first chamber space, wherein fluid pressure at the first port iscommunicated through the signal passage to the first chamber space. 2.The steam pressure regulator according to claim 1, further comprising: aresilient element disposed in the second chamber space, the resilientelement urging the valve toward the first position.
 3. The steampressure regulator according to claim 2, wherein the resilient elementcomprises a spring contiguously engaging the movable actuator wall, thespring opposes displacement of the movable actuator wall due to anincrease in fluid pressure in the first chamber space.
 4. The steampressure regulator according to claim 2, wherein the actuator bodycomprises a third port adapted to provide fluid communication betweenthe second chamber space and ambient conditions outside the actuatorbody.
 5. The steam pressure regulator according to claim 1, furthercomprising: a guide supporting the shaft relative to the valve body. 6.The steam pressure regulator according to claim 5, wherein the guidecomprises a bearing permitting relative sliding movement along alongitudinal axis of the shaft.
 7. The steam pressure regulatoraccording to claim 5, wherein the guide comprises a plurality ofbearings permitting relative sliding movement along a longitudinal axisof the shaft.
 8. The steam pressure regulator according to claim 1,further comprising: a seat fixed with respect to the valve body, whereinthe valve contiguously engages the seat in the first position.
 9. Thesteam pressure regulator according to claim 1, wherein the first port isoriented at a 90 degree angle relative to the second port.
 10. The steampressure regulator according to claim 1, wherein the movable actuatorwall comprises a first portion coupled to the shaft, a second portionsealed with respect to the actuator body, and an intermediate portionconnecting the first and second portions, wherein flexibility of theintermediate portion permits relative movement between the first andsecond portions.
 11. The steam pressure regulator according to claim 1,wherein the actuator body is fixed with respect to the valve body.